High harmonic generation in ferromagnetic thin films as a tool to probe spin and charge dynamics*

High-order harmonic generation (HHG) in solids has garnered worldwide attention [1-3]. The materials include metals, semiconductors, insulators, graphene, fullerenes, and topological insulators. However, this has never been explored for magnetic materials. This study represents the first investigation in the field. We show that HHG in Fe(110) and Fe(001) monolayers carries spin information. If a HHG signal is dispersed into the crystal momentum space, the harmonic peak can be assigned to a single transition, a key step to spin-resolved band structure detection. Different from the optical counterpart, the spin HHG only has even orders. Our findings thus predicts a new frontier of magneto-high-order harmonic generation [4].


[1] S. Ghimire, E. Sistrunk, P. Agostini, L. F. DiMauro and D. A. Reis, Nat. Phys. 7, 138 (2011).
[2] T. T. Luu, M. Garg, S. Yu. Kruchinin, A. Moulet, M. Th. Hassan, and E. Goulielmakis, Nature 521, 498 (2015).
[3] Y. S. You, D. A. Reis and S. Ghimire, Nature Phys. 13, 345 (2017).
[4] G. P. Zhang, M. S. Si, M. Murakami, Y. H. Bai & Thomas F. George, { Generating high-order optical and spin harmonics from ferromagnetic monolayers}, Nature Communications 9, 3031 (2018).